A child's hearing doesn't develop fully until they are about 12-years old. Photo: CC BY 2.0 Travis Isaacs / Flickr
Got a ringing in your ears? It's your brain causing the problem, audiologist Duncan Hann says.
Hann used to suffer from tinnitus - a persistent ringing in the ears - and it prompted him to do a master's thesis on the subject.
Tinnitus was caused by your brain hearing a sound that was being generated by a different part of the brain or body, he told Summer Times.
"The primary purpose of our hearing system is for our survival. So, the startle response. If you hear a sudden loud sound, picture yourself hunting in a jungle, you hear a twig snap behind you - you go into fight or flight."
That automatic reflex, hyper-vigilance, was the same if there was an absence of sound, he said.
"If all of a sudden the jungle goes silent, we still go into fight or flight. Why have the birds stopped chirping? What can they see that we can't see?"
Anything that could trigger a stress response in the hearing system could cause the auditory part of the brain to go into hyperactivity, he said.
"You can think of it as a little bit of inflammation in one part of the brain that is then perceived by a different part of the brain as being real."
The brain would also filter out noise, he said.
"You hang a clock, and it ticks. Initially, your brain tells you to pay attention to that sound, because it doesn't know what it is.
"And then eventually, over time, your brain learns that the ticking is just coming from the clock and that the clock is safe, and so it filters it for you, so you can go about your daily routine without being annoyed by incidental sounds."
But when you heard tinnitus, the brain did not know that it was coming from a different part of your brain, he said.
"It thinks that all sound comes from your environment and is potentially dangerous, so therefore it turns the volume up to get you to pay attention to it."
Although there was no medical cure, there were strategies to manage tinnitus, he said.
The first step was to see an audiologist specialising in tinnitus to get to the bottom of what was causing it for you.
"Tinnitus is heterogeneous, there's lots of different causes and there's lots of different presentations, and therefore the treatments need to be targeted to each individual in terms of what's actually causing their tinnitus."
Silence exacerbated tinnitus, he said.
"One of the most common reports about the presentation of tinnitus is that people hear it when they go to sleep at night, and it's often worse at night purely because people are trying to sleep in silence, but also because they're tired, by definition, their body is under stress and needs rest."
Cognitive behavioural therapy could help here, he said.
"Just understanding tinnitus a little bit more can help the brain's anxiety around tinnitus, so things like avoiding silence and having some sound in your environment that sounds similar to your tinnitus."
Acclimatisation calmed the brain, he said.
"Acclimatisation is getting used to new sounds, like the ticking clock, for example. Your brain is trying to identify, what is that sound, where is it coming from, and is it important?
"With the ticking clock, it can identify over time that the ticking is coming from the clock, it's not important, we're safe. If your brain thinks that the sound that you're experiencing is safe and non-threatening, it can filter it down."
Apps were available that would play sounds similar to the tinnitus sounds, he said.
"It retrains the brain to realise that the sounds are safe, and it can help filter the tinnitus signal down."
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